You keep your inventory, merchant level and customer rep, so making enough money isn't an issue. Be sure to clear out the store first though. Your adventurers should be OP for the first few dungeons, so re-unlocking those shouldn't be a problem either.

Griff is pretty easy to get early on in New Game+. The required events are:- Clear Hall of Trials, Jade Way, and Amber Garden in NG+ (you can skip to the final set of floors in each)- Griff will have two events in the Town Square at Midnight- Next he'll visit your shop sometime at evening or night, to talk.- Louie will visit and tell you about the Obsidian Tower- Clear Obsidian Tower (you can skip to the final set of floors, neither 1-5 or 26-30 are required)- Griff will visit and give you his card(Griff is much more likely to visit if your shop has a dark atmosphere.)

Arma's card is indeed unlocked by completing all of the Lapis Ruins.

Also, since items do carry over, but Pix doesn't, spend all your money on anything you need or want before starting NG+.